Re: [PATCH] mm/secretmem: disable under HIGHMEM

[Mike Rapoport]

On Fri, Jul 03, 2026 at 02:48:26PM +0000, Brendan Jackman wrote:
> secretmem_fault() allocates a folio with GFP_HIGHUSER and then calls
> set_direct_map_valid_noflush() without checking folio_test_highmem().
> This causes a warning and process crash (vibe-coded reproducer in Link
> below):
> 
> Link: https://github.com/bjackman/limmat-kernel-nix/commit/7b2acba2d3a5ef01400d493a155beb1d135b6bb5
> Fixes: 1507f51255c9f ("mm: introduce memfd_secret system call to create "secret" memory areas")
> Signed-off-by: Brendan Jackman <jackmanb@xxxxxxxxxx>

Reviewed-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>

-- 
Sincerely yours,
Mike.